The API can be found at: https://fasjson.fedoraproject.org/ and it shows links to its docs as well.

You can easily query it via curl once you have a valid kerberos ticket, for example:

$ curl --negotiate -u : "https://fasjson.fedoraproject.org/v1/users/paragn/"
{"name": "paragn", "message": "User not found"}
$ curl --negotiate -u : "https://fasjson.fedoraproject.org/v1/users/pingou/"
{"result": {"username": "pingou", ...}

Note that inactive users are shown as non-existing users (which is likely why paragn is not found here while it exists in IPA in fact)

How to activate it? I can't find button in new FAS.

my fas account is readonly. Please set it writable

hm, I see the account as 'enabled' on IPA.

I'll leave this to someone more knowledgeable than me then

This seems a strange case in noggin where theuser exists and is enabled in ipa but doesn't seem to exist in noggin even though they changed their password through noggin 4 days ago. The audit log shows it was the noggin 'user' who changed the password

This issue was caused by the following scenario

1. User existed in ipa from previous logins related to krb auth
2. User was disabled in fas so was not imported
3. User was manually enabled in ipa post migration with no fasUser objectClass so noggin ignored it.

To fix the issue, I ran the fas2ipa import script to pull the user to a local json file. I then modified the file to make the user active and pushed it to ipa.
Note: If doing this in future ensure to use the --skip-groups flag